The present invention generally relates to flexible containers for housing liquid products. More particularly, the present invention relates to multi-chamber containers having a selectively openable seal line between two chambers.
Flexible containers, constructed from plastic films, are commonly used in the medical field for containing, inter alia, parenteral, enteral, and dialysis solutions. A great variety of such solutions can be housed and stored in such containers.
There are, however, a number of products that due to stability, compatibility, or other concerns must be stored in component parts in separate containers and admixed before use. For example, amino acid and dextrose solutions require separate storage containers or compartments. These components, therefore, are stored separately and then mixed prior to use.
One of the disadvantages of storing components in separate containers and then mixing them together is that the mixing process can compromise sterility of the system. Additionally, this step creates a labor intense process.
To deal with the disadvantages of separate containers, it is known to provide multiple chamber containers having an interior including two or more chambers. One way to create such a container is with a heat seal dividing the interior into two chambers. Such containers are disclosed, for example, in U.S. Pat. Nos. 4,396,388; 4,770,295; 3,950,158; 4,000,996; and 4,226,330.
It is known to use frangible valves between the heat seal to allow for selective communication and mixing of the two components stored in the separate chambers. See, for example, U.S. Pat. No. 4,396,488.
However, such a structure--frangible valves--may not be desirable for a number of reasons, including, inter alia, cost. An alternative to frangible valves is disclosed in U.S. Pat. Nos. 3,950,158, 4,000,996 and 4,226,330, where multiple chamber containers are disclosed with a line of weakness, such as a score line, which breaks upon the application of pressure.
In U. S. Pat. No. 4,770,295, a selectively openable seal line is positioned between two sheets of flexible thermoplastic material. The seal line is resistant to unintentional opening forces, but opens upon application of a specific force. The seal line may be employed in various containers, including a two chamber container for the separate storage and selective mixing of two medical substances. The container includes two sheets forming the exterior of the container and an inner diaphragm sheet between the outer sheets. One selectively openable seal is disposed between one of the outer sheets and the diaphragm sheet. A permanent line of securement is preferably included between the exterior sheet and the diaphragm sheet extending substantially parallel to and co-extensive with the openable seal line.
In addition, tear tabs or tear strips for plastic packaging are also known, such as shown in U.S. Pat. No. 2,991,000. Such tear tabs provide access to the contents of the container. However, a disadvantage with these containers is that they also involve the use of relatively complicated seal structures. U.S. Pat. No. 3,983,994 discloses a seal broken by pulling upon tabs located outside of the container.
Another issue that must be considered in constructing containers for the medical industry is that the solutions, and therefore the containers, often require sterilization after manufacture of the container and solution. Typically, the products are sterilized by steam sterilization, or autoclaving. Autoclave sterilization can alter the thermal properties of the film used to form the container and seal between chambers of the container.
Of course, it is desirable to provide a multichamber container with a seal between the chambers that is capable of withstanding external stresses. Such stresses include pressure that may be applied to one or more of the chambers from, for example, squeezing thereof, or accidental dropping of the bag. Therefore, the seal must be sufficiently strong.
However, a difficulty in creating the seal is that the strength of the seal typically increases during sterilization. As a result, a seal may be too strong after the sterilization process making it difficult to separate the seal to combine the components within the chambers.
A need, therefore, exists for a flexible container having chambers separated by a frangible or separable seal that overcomes the disadvantages of the prior art.